The oxidative stability of meat products is of importance with respect to retail shelf life. Oxidative color deterioration in fresh beef, for example, has been estimated to cost U.S. retailers over $1 billion per year due to discounted and discarded product.
At present, refrigeration and packaging are the primary deterrents to oxidative deterioration. Several technologies are utilized, including modified atmospheric packaging (MAP), which involves removing the air from a gas impermeable meat package and replacing the air with various gas mixtures (e.g. 8:2 oxygen:carbon dioxide). MAP can improve meat color (i.e., oxymyoglobin stability), but at the same time gas mixtures that contain high oxygen concentrations negatively affect lipid (and hence flavor) stability owing to the relatively high concentration of oxygen in the package.
Research indicates that supplementation of the animal diet with vitamin E in the form of alpha-tocopherol acetate (ATA) at supranutritional levels is an effective means for improving meat quality (Morrissey, P. A., Buckley, D. J. and Galvin, K. 2000). Vitamin E and the oxidative stability of pork and poultry, in Antioxidants in Muscle Foods, E. A. Decker, C. Faustman and C. J. Lopez-Bote (eds.), pp. 263-287. John Wiley & Sons, Inc.). In addition to improved color, supplementation of the animal diet with ATA results in improved stability of membrane-bound lipids, maintenance of cell membrane integrity, and reduced purge (Monahan, F. J., et al., Food Chem. 1993). ATA does not, however, provide consistent results, and must be incorporated into the animal diet over a fairly long period of time, depending on the dietary concentration. Supranutritional levels of ATA are sometimes used commercially in cattle feed, though not yet for poultry or swine, owing to an inadequate cost-to-benefit ratio.
Therefore, there is a need in the art for cost-effective methods of providing improvements to the tissue quality of an animal with respect to meat quality.
However, to the inventors' knowledge, no one heretofore has studied the effects on meat quality of supplementing the animal feed with a combination of oleic acid and tocotrienols or oleic acid and gamma-tocopherol. Applicants have now discovered that supplementation of the animal diet with oleic acid and either tocotrienols or gamma-tocopherol results in improvements to oxidative stability greater than that observed from oleic acid, tocotrienols or gamma-tocopherol alone.